Since silver halide color reversal photographic materials have a narrow allowable range of exposure, very restricted suitable exposure is required in order to obtain good images. It is based on the fact that they are designed so as to have hard gradation as compared with color negative photographic materials, in order to finally use them as an observable positive image. Therefore, it is necessary to use photographic materials having an optimum sensitivity corresponding to the purpose and exposure condition. However, the photographic materials are not always suitable for satisfying these requirements. Particularly, few color reversal photographic materials sufficiently satisfy these requirement wherein a very high sensitivity is required. Further, exposure to light is not always carried out under optimum conditions, and excess and deficient exposure are not rare. Under such conditions, it has been greatly desired to provide color reversal photographic materials having a high sensitivity and control of sensitivity by treatment for compensating for excess and deficient exposure.
In order to meet these demands, a number of methods of development acceleration or methods of sensitization (desensitization) development have been proposed hitherto. The most general method used hitherto is that wherein the time of black-and-white development is prolonged or wherein the development temperature is raised. Examples of the former are treatment CR-56 for "Fujichrome Professional RD", "ditto RT" and "ditto RH" by Fuji Photo Film Co., and treatment E-6 for "Ektachrome Professional EPR" and "ditto EPD" by Eastman Kodak Co. Examples of the latter are treatment MCR-42/45 for "Fuji Color Reversal RT-125" and "ditto RT-500" by Fuji Photo Film Co. and treatment VNF-1 and RVNP for "Ektachrome VNF" and "ditto VNF high speed" by Eastman Kodak Co.
These methods are simple, because the sensitivity can be increased by changing only the treatment condition, and they are effective particularly when using an automatic developing apparatus. However, these methods have many faults. Firstly, reduction of the maximum density takes place to a great extent with the increase of sensitivity. It is well known that the quality of the images of a color reversal photographic material is greatly influenced by the maximum density. Secondly, color balance varies with increases in the sensitivity. The color balance is also an important matter for determining the quality of images. Thirdly, the time or the temperature necessary to obtain high sensitivity is greatly prolonged or raised, and, consequently, labor and time for the treatment become great.
For the purpose of merely obtaining a high sensitivity, development accelerators have been proposed, for example, in L.F.A. Mason, Photographic Processing Chemistry (Second Edition), pages 41-44, 112 and 113, The Focal Press (1975). Examples of well known accelerators include polyalkylene oxide compounds, sodium thiosulfate, ammonium, phosphonium or sulfonium type onium compounds and polyonium compounds. However, many of such development accelerators have a tendency to increase fog after the treatment of the photographic materials and a tendency to remarkably reduce gamma, whereby good photographic images cannot be obtained.
Further, according to these methods, a high sensitivity can be obtained, but it is difficult to obtain good quality images simultaneously with satisfactory gamma, fog-prevention, granularity in addition to sensitivity even if the condition (for example, time, temperature or etc.) is varied, when using an identical treating solution.
The present inventors studied a method of treatment for eliminating the above-mentioned faults. Namely, it is a method which comprises using a black-and-white developing solution containing a compound represented by the following general formula (I), which causes little increase in the amount of fog, (D.sub.max of the final positive image is high), the development rate is increased, the sensitivity is effectively increased and suitable gradation is obtained.
However, this method of treatment does not always sufficiently satisfy the requirements of users. As indicated above, various sensitivities are required in identical photographic materials. However, when increase of sensitivity is carried out by prolonging the time of black-and-white development according to this method, sensitivities of the blue-sensitive layer, the green-sensitive layer and the red-sensitive layer do not agree with one another, and color tone (the so-called color balance) is damaged.